First plasma experiment on spherical tokamak device UTST

The UTST (University of Tokyo Spherical Tokamak) device was constructed for the purpose of exploring the formation of ultrahigh‐beta ST (spherical tokamak) plasma using the double null plasma merging method. When two plasmas merge together to form a single plasma, magnetic field lines reconnect, and magnetic field energy is converted to plasma kinetic energy, increasing the plasma beta. Merging start‐up has been demonstrated in the TS‐3/4, START, and MAST devices using coils inside the vacuum vessel, and the TS‐3 plasma obtained a 50% beta. In order to demonstrate start‐up in a more reactor‐relevant situation, UTST has all poloidal field (PF) coils outside the vacuum vessel. The first plasma experiment on the UTST was begun in December 2007. In the results, the plasma obtained 10 kA by using only the outer PF coils and a single ST was generated in the lower area (z = –0.3 to –1.0 m) close to a washer gun. This result suggests that another washer gun on the top of the UTST can allow the generation of ST in the upper area and merging start‐up by using outer PF coils. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(2): 20–26, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21216     

A study on physical and mechanical properties for soft to firm clays in Yangon area – Properties of clays deposit at the sedimentary basins in Myanmar

Recently, a great deal of foreign investment has been entered into construction of the social infrastructure of Myanmar. Many construction projects are therefore on-going, and these are especially planned in the Yangon area. While these construction booms are increasing, existing studies on the geotechnical problems in the Yangon area such as problematic soils like soft clays are limited at present. Information on soil properties has also not been shared and has been confined to individual projects. In this paper, the boring and laboratory tests carried out in the Yangon area are selected and focused upon among the tests carried out in Myanmar. Laboratory test results for clay deposits in the Yangon area are analyzed and the differences in soil properties between different sedimentary basins and sub-areas divided by the Tertiary sediment ridge that runs from north to south at the center of Yangon are clarified together with a comparison to the clays found in other countries, which have been previously investigated.     

Comparisons and correlations of phenolic profiles and anti-oxidant activities of seventeen varieties of pineapple

Major phenolic, β-carotene, and ascorbic acid (AA) contents in 17 pineapple varieties were quantified and compared. Anti-oxidant activities were evaluated using 2,2-Diphenyl-l-picrylhydrazyl (DPPH), 2,2’-Azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), ferric reducing anti-oxidant power (FRAP), and metal chelating capacity (MCC) assays. MD-2 exhibited the highest AA and total phenolic (TP) contents and DPPH and ABTS assay results, but was lower in β-carotene contents. Ripley had the highest total flavonoid (TF) content with a low AA content. Comte de Pairs exhibited the highest MCC and the lowest FRAP values. TP contents and both DPPH and ABTS activities, FRAP values and both AA contents and DPPH activities, and TF contents and ABTS activities were positively correlated. MD-2 exhibited the greatest diversity of phenolics and highest anti-oxidant activities in all assays. Information included herein can be useful for development of pineapple-based food products containing high levels of health promoting anti-oxidants.     

Applications of microstructures fabricated by proton beam writing to electric-micro filters

Fabrication of high-aspect-ratio microstructures was performed by proton beam writing (PBW) using a microbeam line at Takasaki Ion Accelerators for Advanced Radiation Application (TIARA), JAEA Takasaki, JAPAN. As one of the applications of the high-aspect-ratio structures micro-machined by PBW, we utilized the high-aspect pillars for electric-micro filters of microbes such as Escherichia coli and Yeast based on the dielectrophoretic force. The filter is equipped with high-aspect pillars with a height of ～20 μm and a diameter of ～1 μm on a glass plate. Evaluation of the dielectrophoresis (DEP) device for capturing E. coli and Yeast was made using either observation by optical microscope or photoluminescence (PL) measurements.     

Effect of wall wettability condition on drift-flux parameters in lead–bismuth two-phase flow in circular and annular bubble columns

Lead–bismuth two-phase flow in a cylindrical vessel and annulus was experimentally investigated by varying the surface wettability of the vessel wall. The test section used in this study was a cylindrical stainless vessel with/without inner sleeve to change the hydraulic diameter. Volume-averaged void fraction was measured by varying the surface wettability of the test section, which was enhanced by using a soldering flux. Measured void fraction was compared with existing two-phase flow correlations and with one-dimensional theoretical simulations assuming one-dimensional drift-flux model. From experimental results, measured distribution parameters of the lead–bismuth two-phase flow are much larger than that of ordinary two-phase flow regardless of the surface wettability. In the present work, the one-dimensional analysis was carried out for the cylindrical vessel to reproduce the distribution parameter. From the simulation results, predicted value for the cylindrical vessel showed good agreement with experimental results. However, in annulus, the distribution parameters in annulus were underestimated by the present model. It was suggested that, in case of annulus, steeper void fraction profile might be formed near the inner surface for poor wettability condition.     

All solid-state battery with sulfur electrode and thio-LISICON electrolyte

A high-capacity type of all solid-state battery was developed using sulfur electrode and the thio-LISICON electrolyte. New nano-composite of sulfur and acetylene black (AB) with an average particle size of 1–10 nm was fabricated by gas-phase mixing and showed a reversible capacity of 900 mAh g⁻¹ at a current density of 0.013 mA cm⁻².     

Prolonged Aftereffect of Visuomotor Adaptation to Gradually Distorted Reality Displayed on a See-Through Head-Mounted Device

Growing evidence suggests that the gradual transformation of visuomotor association drives a distinct learning process from abrupt transformation in humans. In the current study, we developed a novel omnidirectional visuomotor transformation paradigm to study details of such difference in more realistic environment than conventional experimental systems. Participants were asked to perform a repetitive three-dimensional (3D) arm-reaching task to a target on a front touch panel, wearing a video see-through head-mounted device that displayed a rotating view of surrounding images. In the abrupt condition, the images were rotated by 20°; in the gradual condition, the rotation was increased in a stepwise-manner from 0° to 20°. In both conditions, pointing errors were decreased after adaptation. Further, although the aftereffect of adaptation was not different between conditions, the speed of decay of the aftereffect, which was quantified by an exponential fit, was slower in the gradual condition, suggesting longer-lasting aftereffects for the gradual shift.     

Examination of pin-by-pin fission rate distribution in large geometry evaluated by the Monte-Carlo method

Accuracy and reliability of pin-by-pin fission rate distribution in large geometries calculated by the multi-group Monte-Carlo method is examined through comparison with a deterministic transport code based on the method of characteristics. Various calculation geometries from a single assembly to a PWR full core are used for comparison of pin-by-pin fission rate distribution. An integral parameter, i.e., k-effective, can be accurately calculated by the Monte-Carlo method with a practical number of neutron histories (10⁶–10⁷) regardless of the size of the calculation geometry. On the other hand, comparison with the deterministic calculation shows that the estimated statistical errors for pin-by-pin fission rate distribution obtained by a Monte-Carlo calculation are somewhat underestimated in a large geometry, e.g., a PWR full core, under the present calculation conditions. Such underestimation of the statistical uncertainty of a local parameter should be carefully considered when the Monte-Carlo method is used as a reference tool for verification of a deterministic code, especially in large geometries.